ugh, that sucks dude. happened to me once with an older cooler master aio. generally, grinding noises mean the pump is dying. not really repairable, sadly, since they're sealed units. you *could* try tilting your case around to dislodge any air bubbles, sometimes that helps if it's just air trapped, but if it's actual grinding, it's usually terminal. sounds like it's time for a new one, tbh.